1. Field of the Invention
The present invention relates to an audio processing apparatus having a first output terminal for outputting an audio signal to a first speaker arranged in a first room, and a second output terminal for outputting an audio signal to a second speaker arranged in a second room.
2. Description of the Related Art
FIG. 11 is a block diagram illustrating a constitution of a conventional AV amplifier 101. The AV amplifier 101 is connected to a plurality of BD (Blu-Ray Disc) players 20A and 20B. Digital audio signals are input from the BD players 20A and 20B into digital audio input terminals IN1 and IN2, and analog audio signals are input into analog audio input terminals IN3 and IN4. The AV amplifier 101, BD players 20A and 20B, and a main speaker 30 are arranged in a main room, and a ZONE2 speaker 40 is arranged in a ZONE2 room.
An audio signal to be output to the main speaker 30 will be described. A digital audio selector 2 selects one digital audio signal from digital audio signals supplied from the BD players 20A and 20B, and supplies this signal to a DSP 6. An analog audio selector 3 selects one analog audio signal from analog audio signals supplied from the BD players 20A and 20B, and supplies this signal to an ADC 5. The ADC 5 converts the analog audio signal into a digital audio signal, and supplies the digital audio signal to the DSP 6. Actually, only the digital audio signal from any one of the digital audio selector 2 and the analog audio selector 3 is supplied to the DSP 6. The DSP 6 executes an audio process on the supplied digital audio signal, and supplies the processed signal to a DAC 7. The DAC 7 converts the supplied digital audio signal into an analog audio signal, and supplies the converted signal to an amplifying section 8. The amplifying section 8 amplifies the supplied audio signal, and outputs the audio signal to the main speaker 30 via a speaker output terminal 9 for the main speaker.
An audio signal to be output to the ZONE2 speaker 40 will be described. An analog audio selector 4 selects one analog audio signal from analog audio signals supplied from the BD players 20A and 20B, and supplies the selected signal to an amplifying section 10. The amplifying section amplifies the supplied audio signal, and outputs the amplified audio signal to the ZONE2 speaker 40 via a speaker output terminal 11 for the ZONE2 speaker. Only an analog audio signal from the analog audio selector 4 can be output to the ZONE2 speaker 40, and thus digital audio signals input into the digital audio input terminals IN1 and IN2 cannot be output from the ZONE2 speaker 40.
The main room is, for example, a living room, and the ZONE2 room is a room adjacent to the living room (for example, a child room or a kitchen). Doors between these rooms are opened, and the main room and the ZONE2 room are occasionally used as one big room. At this time, it is assumed that the same audio signals from the BD player 20A or 20B are output as BGM to the main speaker to be arranged in the main room and the ZONE2 speaker to be arranged in the ZONE2 room. However, the audio signal to be output to the main speaker 30 is subject to the audio process in the DSP 6, and the audio signal to be output to the ZONE2 speaker 40 is not subject to the audio process in the DSP. For this reason, the audio signal to be output to the main speaker 30 is delayed by the time for the audio process in the DPS 6 with respect to the audio signal to be output to the ZONE2 speaker 40. As a result, the audio signal to be output from the main speaker 30 and the audio signal to be output from the ZONE2 speaker 40 are not output simultaneously, thereby providing a sense of discomfort to listeners.
In order to solve this problem, the following method is present. In this method, the analog audio signal to be supplied from the analog audio selector 3 is supplied directly to the amplifying section 8 without via the ADC 5, the DSP 6 and the DAC 7, so as to be output to the main speaker 30. In this case, however, the DSP 6 cannot generate surround audio signals (for example, a central audio signal C, a surround left audio signal SL, a surround right audio signal SR, and a lowpass audio signal SW) based on analog audio signals including a left-front audio signal L and a right-front audio signal R. For this reason, an audio cannot be output from speakers of these channels in the main speaker 30.